Various photovoltaic (PV) monitoring systems have been designed to facilitate measurement of such factors as module and array performance, grid stability, islanding, power factors, etc. Such monitoring systems can be built into inverters or converters and designed to connect/disconnect from the grid during low or high voltage events, prevent islanding, and report on PV status (e.g., current, voltage, power, etc.).
PV monitoring system concepts are designed to detect, classify, and/or locate faults when system behavior deviates from an expected operating condition. To facilitate prediction of an expected PV performance at a given time, various PV system models utilizing inputs from meteorological condition(s) have been created. These models can calculate expected power using such information as temperature and irradiance data gathered from sensors associated with a module/array, a transmission system(s), a weather monitoring system(s), a satellite system(s), etc. PV system models which have been utilized include PV circuit models, PV plant-specific fits, matter-element models, expert systems with updating warning criteria, etc. The PV system models, operating in conjunction with such measurements as current, voltage, power, etc., from the physical PV system are utilized to detect a number of fault conditions such as shading, inverter failure, snow cover, module failures, module short circuiting, string-level malfunctions, etc.